Central nervous system (CNS) involvement represents a common complication in systemic lupus erythematosus (SLE). Diagnosis and therapy of severe neuropsychiatric disease remain a challenge to the clinician. The clinical data of 171 inpatients with CNS-SLE in Peking Union Medical College Hospital from January 1980 to June 1998 were retrospectively reviewed for understanding and better management of this challenging complication. The incidence of CNS involvement in SLE was 14.2%. The mean SLE duration at onset of CNS-SLE was 2.21 +/- 1.87 years, with 132 (77.2%) occurring within 2 years. A cerebral spinal fluid abnormality was seen in 91.4% (138 of 151) of CNS-SLE, with protein elevation in 113 (74.8%), pressure elevation in 69 (45.7%), and white cell elevation in 51 (33.8%, 42 cases were <100 x 10/L), glucose reduction 6 (4.0%). The positive rates of anti-P in diffuse CNS-SLE and SLE with epilepsy were significantly higher than in non-CNS-SLE (p < 0.05). Although not reaching a significant level, they were also tending to be higher than in focal CNS-SLE. On the contrary, the positive rate of ACL in focal CNS-SLE was significantly higher than in the diffuse type or non-CNS-SLE (p < 0.01). The total mortality rate in 171 patients with CNS-SLE was 18.7% (32 cases); however, the mortality rate since 1993 (4.0%, 3 of 75) was much lower than before (30.2%, 29 of 96, p < 0.01). Of 24 CNS-SLE patients who received intrathecal injections with dexamethasone plus methotrexate, 22 (91.7%) improved considerably. To improve the outcome of CNS-SLE, early diagnosis and aggressive therapy are essential. Cerebral spinal fluid analysis is proposed as the most fundamental test. Intrathecal injection might be a useful alternative for those patients with CNS-SLE refractory to conventional therapy.